There has conventionally been known the method (asymmetric hydrolysis) for preparing a carbonyl compound or the hydrolysate, in increased optical purity, which comprises hydrolyzing an optical isomer mixture, such as an enol ester, in the kinetic manner to hydrolyze preferentially either one of the optical isomers, or the method (dissymmetrization procedure) for increasing the optical purity of an enol ester.
With reference to the asymmetric hydrolysis method, for example, JP 10-84988-A describes that an enzyme originating from the genus Candida is allowed to act on a 3-acyloxyfuran, or an enol ester, to produce a 3-(2H)-furanone possessing the optically active α-position to the carbonyl group, while in J. Am. Chem. Soc., 1990, 112, 9614-9619, there is reported that an enzyme originating from the genus Pichia or an esterase from the porcine liver is allowed to act on a 1-acyloxy-2-alkylcycloalkene to produce an optically active α-alkylcycloalkanone.
However, these methods involve merely asymmetric induction of the carbonyl group to the α-carbon atom which results from hydrolysis of enol esters, and there naturally neither been described nor suggested any asymmetric induction to a carbon atom which is relatively distant from the carbonyl group.
Referring now to the dissymetrization procedure, for example, there is mentioned in Tetrahedron Letters, 38, (1997) 7781 that racemic cyclohexene-1-yl acetate having cyano and phenyl groups at the 4-position is allowed to hydrolyse the (R) isomer preferentially with use of a lipase originating from a microorganism of the genus Pseudomonas to thereby produce an enol ester of the (S) isomer in 100% ee via conversion to a ketone derivative, and in Chemistry Letters, pp. 1109, 1989, there is reported that by allowing a microorganism of the genus Bacillus to act on an enol ester having two of three hydroxyl groups protected, dissymetrization is carried out to give an enol ester of the (R) isomer in optical yield of not less than 95% ee, while Tetrahedron Letters, 40, (1999) 8633, describes that an enol acetate derived from a 1,5-di-substituted-8-oxabicyclo[3.2.1]-6-octen-3-one is subjected to a dissymetrization procedure, in the presence of hexane and n-butanol, with a lipase originating from a microorganism of the genus Humicola as adsorbed onto silica gel to produce an optically active enol acetate in max. 99% ee.